# ---
# title: 941. Valid Mountain Array
# id: problem941
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: Array
# link: <https://leetcode.com/problems/valid-mountain-array/description/>
# hidden: true
# ---
# 
# Given an array of integers `arr`, return _`true` if and only if it is a valid
# mountain array_.
# 
# Recall that arr is a mountain array if and only if:
# 
#   * `arr.length >= 3`
#   * There exists some `i` with `0 < i < arr.length - 1` such that: 
#     * `arr[0] < arr[1] < ... < arr[i - 1] < A[i] `
#     * `arr[i] > arr[i + 1] > ... > arr[arr.length - 1]`
# 
# ![](https://assets.leetcode.com/uploads/2019/10/20/hint_valid_mountain_array.png)
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: arr = [2,1]
#     Output: false
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: arr = [3,5,5]
#     Output: false
#     
# 
# **Example 3:**
# 
#     
#     
#     Input: arr = [0,3,2,1]
#     Output: true
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= arr.length <= 104`
#   * `0 <= arr[i] <= 104`
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
